UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.87 Safari/537.36

Steps to reproduce the problem:
1. visit https://jsfiddle.net/t7pn974a/1/
2. click "Run"
3. JSON.stringify() will throw this error 
"Uncaught TypeError: Converting circular structure to JSON"

What is the expected behavior?
The stringify() should execute without an error.

What went wrong?
Chrome v48, IE11, and Firefox v43 will execute the stringify() without any errors.

It looks like this issue only occurs if the model is set up in the same way as in the jsfiddle. Specifically, the toJSON() function on the model has to be bound to "this", and the model has to have a change event.

Did this work before? Yes Chrome v48

Chrome version: 49.0.2623.87  Channel: stable
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 21.0 r0

If you put a dummy "replacer" function in the stringify() call, the issue does not occur.

var replacer = function (key, value) {
   return value;
}
JSON.stringify(model, replacer);